Your vote, if not initialed, is not immediately informal.
We don't look for the initials in counting, neither do the scrutineers - it would only be detected at the formal recount back at HQ, where the principle is always to give effect to the voters intention.
At my OIC training, this question was asked, and the divisional officer said there that he had never ruled a vote informal just based on the ballot missing an initial.
With so many workers and so many millions of voters, there would be a reasonable assumption that there would be a number of votes missing an initial, overlooked by that worker.
That makes me feel better -- thanks for that